Past methods and apparatuses for administering fluids to a stationary or ambulatory patient have primarily involved holding the source of the fluid above the patient and relying on the gravitational forces to deliver the fluids into the patient. Other methods and apparatuses rely on the venturi action of the patient's own vascular system to deliver the fluids into him. Still others use electric pumps powered by stationary or portable storage cells that can be wet or dry batteries.
Many of these systems are impractical or unreliable in emergency situations, especially battlefield emergencies. For example, it is often difficult or impossible to maintain a fluid source above a patient for gravitational feed when the patient is being rushed on a stretcher to a hospital. If the patient is being carried from a battlefield, the situation is even worse since the attendants have to concentrate more on safe movement of the patient than on keeping the fluid source held above him. Further, if it is absolutely necessary that the fluid source be held above the patient, an extra attendant is required. This additional attendant can be a very costly item on the battlefield and will greatly reduce the overall efficiency of the military and medical teams.
Systems using the venturi action of the patient's own vascular system often find the pulse of the patient too weak or irregular to be effective. These systems require constant visual monitoring by a medical attendant to make sure the patient is receiving the fluids properly. As with the gravitational systems, this exta attendant can be a most unfortunate waste of precious medical personnel.
The methods and apparatuses using electrical pumps have also proven to be unsatisfactory. Electrical pumps have numerous moving parts that can fail in addition to the paramount problems of battery upkeep and failure. These systems must be constantly checked while in storage and in use. Battery failure is usually unpredictable as well as being sudden and complete. Electrical systems are almost impossible to maintain in battlefield conditions, especially in bad weather and, furthermore, they are often bulky, costly and difficult to handle.
The ideal portable pump for intravenously feeding fluids to a patient would be simple, reliable, safe, sterile, inexpensive to make, and able to administer fluids with the source vessel above or below the patient. It would also have an adjustable pumping rate and stroke as well as interchangeable, disposable, and reuseable parts. Further, it would need a minimum of personnel and effort to operate, would not require constant visual monitoring, and would be easily and quickly convertible to a gravity feed system should the pumping mechanism fail. The present invention provides such a pump.